THIS DELICIOUSLY entertaining and fiercely intelligent book is something of an anomaly -- though certainly a most welcome one -- in contemporary American fiction. Hard Money is neither highbrow nor lowbrow, as most American novels now tend to be, but it isn't middlebrow either. It occupies instead the territory once claimed by writers as various (and variously gifted) as Theodore Dreiser, John Dos Passos, John P. Marquand and James Gould Cozzens. It is a large, ambitious novel that seeks both to tell a good story and to call into question the ways in which Americans do business both literally and figuratively. The extent to which it succeeds is impressive indeed; though not without its minor flaws -- its beginning may seem excessively leisurely to some tastes, and its narrator never really enters into a plausible relationship with a woman -- it is a book of such wit, vigor and immediacy that it deserves both a large audience and critical respect.

It is the story of the last years of Xenophon Horace Hubert Monstrance, known to its narrator and other personal friends as X, "the legendary tycoon, entrepreneur, impresario, financier, charmer, warrior, seducer." In 1932 he started the Granite Broadcasting Group with three radio stations; by his retirement a couple of years ago he had built it into "the most commanding presence in American entertainment and communications, bigger and more influential than CBS, more 'commercial' and profitable than ABC." Now, though, GBG has been swallowed up into AbCom, the hugely profitable corporate monster constructed by X's brilliant, obsessive son, Abner. The money still rolls in, but ratings are down and so is X's sense of self-esteem. "I had built this company," he says, "this industry, into what I flattered myself into thinking was a monument for the ages, and what had I really built? A golden barge named GBG floating atop a great, poisonous, stinking tidal wave of garbage. I had seduced the nation into relying on television for its understanding of the world and for its values, and I had given it lies and delusion."

This is said to Sam Mountcastle, the narrator, a magazine journalist who has known the Monstrance family virtually all his life and whose feelings toward X, though complex, border on the filial. He has been out of the Monstrance orbit for a quarter- century, but now is drawn back into it by X, who, at the age of 75, proposes a bold return to GBG and offers Sam the chance to chronicle it from the inside. His real purpose is not to reverse the slide in GBG's ratings but to seek atonement, not merely for the deleterious role television has come to play in American life but for his own role, however unwitting, in the elevation of a shallow talk-show performer, "a combination of cupidity and stupidity," into the presidency of the United States. X hopes that Abner will welcome him back into the company and encourage his efforts to make television responsive to the public interest; but if the response is hostile, X is prepared to fight.

These obviously are the basic ingredients of boardroom soap opera, and there's a touch of that in Hard Money; but life itself, as John Irving has pointedly reminded us, is soap opera. The people about whom Michael Thomas writes are playing for almost unimaginably high stakes, so it stands to reason that in their story there will be exaggerated drama, emotion and suspense. What matters about Hard Money in any event is not the plot -- no further details of which will be revealed herein -- but the people who flesh it out and the momentous issues with which they are confronted. It is here that Hard Money rises out of the realm of commercial fiction and into a meditation on American society and values that really does recall Dreiser, though in considerably more felicitous prose.

It is a novel about "a culture and an era to whom effrontery and vulgarity were no longer bad," a hilarious yet ferocious condemnation of the new rich of the 1980s, the "social climbers, stock market papermongers, real estate shills and assorted other virtuosos of hype and blather" who now control Manhattan and the territories with which it does business: "a miserable collection of shameless opportunists and gratification seekers: the men were principally paper merchants gorged on inside info and big lines of credit; the women were marked by a social ambition so obvious as to be unconscionable; the whole lot were vulgar, loud, unlettered, parasitic, and marked, above all, by an insecure, humorless self-esteem based on and derived from possessions." Sam Mountcastle moves among them with unease and anger:

"Abner's new breed was beyond my appreciation, almost beyond my understanding, with its cocksure assumption that people like me, little people, subconsciously defined in his mind as all of us who didn't lodge in forty- fifth-floor suites with three secretaries and helicopters on ready alert, were just so many manipulable bits of data, minute fractions of information to be summoned at will from the innards of his computer and reshaped and reorganized to suit the requirements of himself and the other power people."

POWER IS OF course the central subject of Hard Money: its uses and abuses, its temptations and attractions, its corruptions and debasements. Before the book has ended a great many people have been destroyed by their thirst for it, and the Monstrance family has been left in a shambles by the destructive rivalries it arouses. But in contemplating power Thomas casts his eye across an entire continent and into a new age, one in which "the new religion . . . proclaimed that everything had its price and by rights belonged to him who could pay it," in which "politics and money were fused and indistinguishable," in which the nation "reserves its welfare for the rich."

The people in whose lives these themes emerge are a luridly fascinating lot. X is a brilliantly realized character, an entirely convincing mix of megalomania and conscience, a pervasive presence whose longing for a "stamp on posterity" at last moves him to noble action. The fast-buck operators with whom he is surrounded are an oily crew -- as one earthy character puts it, "we sure got the scummiest buncha billionaires in the whole recorded history of money" -- whose depredations and self-indulgences Sam Mountcastle records in telling, contemptuous detail. Mountcastle himself is a person of depth and complexity, a writer who lives in "the real world" rather than the literary hothouse and who is passionately committed to his values and beliefs:

"What I wanted now was to write well and for what I wrote to make some kind of a difference, to change a world I found grasping, smarmy, sleazy, illiterate, shallow, choked. Just what X said he wanted to accomplish: to make television better, and to have it make our lives better by revealing things the way they were. No matter what people said, I wrote out of rage, not pique; out of reflection, not envy. It was as I had tried to explain . . . : in an age which makes a state religion out of euphemism, a realist will be damned and demeaned as a cynic. There are always naked emperors about, and they always have their tailors with them."

There can be no doubt that in this passage Sam Mountcastle speaks for Michael Thomas, and Hard Money amply demonstrates that he speaks accurately. It is a novel that throbs with deep feeling, that shows its author's own values and commitments on every page. Yet for all its anger and passion it is a wonderfully humorous and compan book. On all the levels that matter it is a stupendous performance, and I recommend it with real enthusiasm -- not merely for "summer reading," though it will provide that handsomely, but for the best reading of all, that which enriches our understanding of ourselves.